🎲 Betting Odds Converter

Sportsbooks display odds in different formats depending on region and platform. American odds show +150 (bet 100 to win 150, plus your stake back = 250 total) or −200 (bet 200 to win 100, plus stake back = 300 total). Decimal odds, common in Europe, show your total return multiple including stake (e.g. 2.50 means a $1 bet returns $2.50). Fractional odds, used in the UK, show 3/2 meaning "bet 2 to win 3." Conversion formulas: positive American → Decimal = (American/100)+1; negative American → Decimal = (100/|American|)+1; Decimal → Fraction = reduce (Decimal−1) to lowest terms; Decimal → Implied probability = (1/Decimal)×100. For example, American +150 converts to Decimal (150/100)+1 = 2.50, Fractional 3/2, and implied probability (1/2.50)×100 = 40%.

Implied probability is the chance of an outcome that a given set of odds suggests, calculated as Implied probability = (1 ÷ Decimal odds) × 100. For example, decimal odds of 2.50 imply a 40% probability. In practice, if you add up the implied probabilities for every possible outcome of an event (e.g. team A wins, team B wins, draw), the total usually exceeds 100% — often by several percentage points — because bookmakers build in a margin (called the "overround" or "vig") by pricing odds slightly lower than the true probability would justify. If the three outcomes sum to 106% implied probability, roughly 6% is the bookmaker's built-in margin. So the implied probability calculated from posted odds is not a "fair" probability — it already bakes in the house edge. This tool only performs the mathematical conversion between notations; it does not predict outcomes or offer betting strategy.